C#

Dave Kreskowiak wrote:

context of "beginner"

using System;
using System.Collections.Generic;

namespace YourNameSpace
{
    public enum Fruit
    {
        NoFruit, Apple, Orange
    }

    public class FruitCalc
    {
        private Dictionary<Fruit, Func<int, int, Fruit>> CalcFruitDict
            = new Dictionary<Fruit, Func<int, int, Fruit>>
            {
                // lambda notation used here
                {Fruit.Apple, (int napples, int noranges) => napples > noranges ? Fruit.Apple : Fruit.NoFruit },
                {Fruit.Orange, (int napples, int noranges) => napples < noranges ? Fruit.Orange : Fruit.NoFruit },
            };

        public Fruit Calculate(Fruit fruit, int napples, int noranges)
        {
            if (fruit == Fruit.NoFruit)
            {
                throw new InvalidOperationException("Sorry, no fruit means no fruit");
            }

            // check integer parameters for valid range ?

            return CalcFruitDict[fruit](napples, noranges);
        }
    }
}

FruitCalc fcalc = new FruitCalc();

Fruit f1 = fcalc.Calculate(Fruit.Apple, 12, 4);
Fruit f2 = fcalc.Calculate(Fruit.Orange, 14, 24);

Fruit f3 = fcalc.Calculate(Fruit.Apple, 2, 4);
Fruit f4 = fcalc.Calculate(Fruit.Orange, 14, 2);

// force an error
Fruit f5 = fcalc.Calculate(Fruit.NoFruit, 12, 4);

public Fruit Calculate2(Fruit fruit, int napples, int noranges)
{
    switch (fruit)
    {
        case Fruit.Apple:
            return napples > noranges ? Fruit.Apple : Fruit.NoFruit;
        case Fruit.Orange:
            return napples < noranges ? Fruit.Orange : Fruit.NoFruit;
        default:
            throw new InvalidOperationException("Sorry, no fruit means no fruit");
    }
}

public void DropDownSelectChanged(object sender, EventArgs args)
{
  // assuming the sender is the drop down
  var ddl = sender as DropDown; // whatever the actual control is in your GUI
  Calculate(ddl.SelectedItem);
}

// These get set in your constructor.
public Action MoreApplesAction {get; set;}
public Action FewerApplesAction {get; set;}

public void Caclulate(Fruit selectedFruit)
{
  // Of course, these should be properties somewhere
  var Apple = 5
  var Orange = 1

  // It's OK to create guards like this to
  // enhance readability, but don't be surprised
  // when someone objects because of the memory
  // allocation.
  var MoreApples = Apple > Orange;
  var FewerApples = Apple < Orange;

  switch(selectedFruit)
  {
    case Apple:
      if(MoreApplies) MoreApplesAction?.Invoke();
      break;

    case Orange:
      if(FewerApples) FewerApplesAction?.Invoke();
      break;
  }
}

// required
// using System.Collections.Generic;
// using System.IO;
// using System.Linq;

public class Person
{
    public Person(string name, int age, int telNum, string emailId)
    {
        Name = name;
        Age = age;
        TelNum = telNum;
        EmailId = emailId;
    }

    public string Name { get; set; }
    public int Age { get; set; }
    public int TelNum { get; set; }
    public string EmailId { get; set; }
}

// 2 define a factory that reads a file, and creates a List<Person>

public static class PersonFactory
{

    static char[] delimiter = new []{','};
    
    public static Person MakePerson(string line)
    {
        try
        {
            var data = line.Split(delimiter, StringSplitOptions.RemoveEmptyEntries);
            var name = data[0];
            var age = Int32.Parse(data[1]);
            var tel = Int32.Parse(data[2]);
            var eml = data[3];
    
            return new Person(name, age, tel, eml);
        }
        catch (Exception ex)
        {
            throw new InvalidDataException(ex.Message);
        }
    }
    
    public static List<Person> PersonsFromFile(string filepath)
    {
        // note use of Skip to ignore first line
        // which contains header informatiomn
        var lines = File.ReadAllLines(filepath).Skip(1);
    
        return lines.Select(line => MakePerson(line.Trim())).ToList();
    }
}

var persons = PersonFactory.PersonsFromFile(@"C:\Users\###\##\##?.txt");
            
int chrisage = persons.First(p => p.Name == "Chris").Age;

Member 14571520 wrote:

I am having trouble constructing these matrices..

public class MyData
{
    private System.Globalization.CultureInfo ci = new System.Globalization.CultureInfo("en-US");
    public string Name {get; set;}
    public string Institute {get; set;}
    public int X {get; set;}
    public int Y {get; set;}
    public string[] Headers {get; set;}
    public double[][] DataMatrix {get; set;}
    public MyData(string sFileName)
    {
        if(!File.Exists(sFileName))
            throw new FileNotFoundException($"File '{Path.GetFileName(sFileName)}' does not exist!");

        string[] lines = File.ReadAllLines(sFileName);
        Name = lines[0];
        Institute = lines[1];
        X = Convert.ToInt32(lines[5].Split(' ')[0]);
        Y = Convert.ToInt32(lines[5].Split(' ')[1]);
        Headers = lines[7].Split(new string[]{" : "}, StringSplitOptions.RemoveEmptyEntries);
        DataMatrix = lines.Skip(9)
            .TakeWhile(l=>l.Length>0 && !l.StartsWith("."))
            .Select(l=>l.Split(' ').Select(d=>Double.Parse(d, ci)).ToArray())
            .ToArray();
    }
}

string filename= "C://user//abc.txt";
MyData md = new MyData(filename);
Console.WriteLine(md.Name);
Console.WriteLine(md.Institute);
Console.WriteLine("X = {0}, Y = {1}", md.X, md.Y);
double[] allMasses = md.DataMatrix.Select(m=>m[0]).ToArray();
foreach(double d in allMasses)
    Console.WriteLine(d);
//on the same manner you can get Weight, Time, Velocity, Acceleration and Distance

Member 14571520 wrote:

MandW = new matrix(x,2); /* Mass and Weight Matrix*/

MandW = new double[x,2]; /* Mass and Weight Matrix*/